1. Field of the Invention
The present invention provides a two circuit brake, tail and turn signal light emitting diode lamp.
2. Description of the Prior Art
Light emitting diode lamps have been used to replace incandescent lamps used in automobiles and other motor vehicles and to replace LED lamps for both single filament and dual filament incandescent bulbs. LED's typically operate at voltages between 1.7 and 2.2 volts.
A typical prior art incandescent lamp generally employs a type S-8 glass bulb cemented in a brass bayonet base having dual contacts. A similar incandescent lamp is described in Devir et al., U.S. Pat. No. 4,603,278. Incandescent vehicle signal-lamps consume a relatively large amount of power, generate a large amount of heat and have a relatively short life.
LED lamps designed to replace vehicle incandescent lamps require bases similar to the standard bayonet base. To be effective an LED lamp must be adapted to produce an intense light when viewed by the human eye and must provide for effective heat dissipation to avoid impairing the LED's. It also must be designed to operate within the range of voltages present in motor vehicles so as to not over-voltage the LED's. Finally, some models of motor vehicles ground the brake circuit when the brake is not activated to prevent any accidental activation of the brake lights; accordingly, an effective LED lamp designed to replace a dual filament lamp must contain circuitry enabling the LED's to be activated with either the tail lamp circuit or the brake light circuit.
U.S. Pat. No. 6,371,636 to Wesson teaches a light emitting diode lamp for use in vehicle tail, brake or turn signal lamp fixtures for integrated single and dual element operation. The module has integrated dual element control circuitry, voltage and current control circuitry, brightness enhancement circuitry, and LED circuitry built into the universal body. All the LED's are energized if either the tail lamp or brake lamp circuits were energized.
U.S. Pat. No. 6,598,996 to Lodhie provides a light emitting diode lamp for use in a brake light bulb socket of an automobile or similar vehicle. The light emitting diode lamp can be used as both a brake signal and a turn signal. The light emitting diode lamp includes first and second printed circuit boards having first and second pluralities of light emitting diodes mounted thereupon for emitting monochromatic light in response to power signals supplied from the automobile. The light emitting diode lamp further includes a body adapted to form a bayonet connection, a base having at least one contact, and a support sleeve having a wiring conduit, a support tray, and at least two support stanchions for supporting the first printed circuit board. The light emitting diode lamp also includes an electrical control means electrically connecting the first and second contacts with the first and second printed circuit boards, and a lens cap having a planar front face integrally formed with a cylindrical lens sidewall that terminates in a lens perimeter. The support sleeve supports first and second printed circuit boards in an operable relationship for maximum output of monochromatic light while maintaining high impact resistance. All the LED's are on full intensity in the brake light mode and, via a contact switch in the base, all LED's are on at low intensity for the tail light mode using a single or a plurality of resistors.
Although the diode lamp disclosed in Lodhie performs extremely well, it would be desired if the lamp can be operated in a manner where selected lamps in both modes are operated in full intensity thus avoiding the use of resistors to dim or reduce the intensity of the LED's.
What is desired is to provide a LED bulb having a bayonet base and wherein different groups of LED's are energized depending upon whether the car is in the tail light or brake light mode.